Natural cheese of the American type (e.g., cheddar or Colby) is manufactured by coagulating ripened milk of proper acidity with rennet, cutting the coagulant, and cooking the resulting curd, whereupon the curd is pressed and further whey removal is effected. The desired flavor, aroma, and texture of the cheese is obtained by curing which involves holding the cheese for a time at desired temperatures.
The moisture content of hard cheeses is important as it impacts the texture of the product. The fat content of hard cheeses is important as it significantly influences the sensory properties thereof by aiding the production of flavor, aroma, and body in cured cheese. The minimum milk fat and maximum moisture content of most cheeses is regulated by Federal and state regulations. For example, in the United States, hard cheddar cheese should have a minimum milk fat content of 50 percent by weight of the solids, and a maximum moisture content of 39 percent by weight. However, reduced fat and low fat cheeses are desired by many consumers, which typically have lower fat content and higher moisture content than the standard hard cheeses. In order to comply with U.S. Standards of Identity applicable to reduced fat cheddar cheeses, for instance, cheddar cheese may be manufactured to contain approximately 33 percent less fat and up to approximately 20 percent more moisture than standard cheddar cheese.
Natural cheeses, including reduced fat natural cheeses, have been produced in a variety of unit sizes. In cheese production, however, it is desirable to produce large rectangular blocks of cheese which, for example, may weigh approximately 640 pounds. These large blocks of cheese can be conveniently divided into smaller blocks or shredded, and packaged for retail.
In conventional production of such large blocks of cheese, cheese curd is separated from free whey, and then the drained curd is placed in a bulk container for pressing. In the instance of cheese blocks, the container is provided with openings through which the whey drains as the curd is pressed. This procedure is varied somewhat for the manufacture of cheese barrels, in which the cheese curd may be sealed prior to and during pressing.
It is common practice in the manufacture of cheddar and like types of cheese to cool the large pressed blocks of cheese from the manufacturing temperature of about 85-90° F. to a refrigerated temperature of about 32-40° F. Such large blocks of cheese take multiple days to cool from the manufacturing temperature of 85-90° F. to the cold room temperature of about 32-40° F. The cheese is then stored under conditions and for a period of time conducive for curing the cheese.
In the making of large cheese blocks, it is desirable that the moisture content be uniform throughout the block. In prior cheese manufacture, however, a moisture gradient has been observed to occur in the cheese blocks during the cooling period. Moisture has tended to migrate from the core or central region of the cheese blocks towards the exterior surfaces. For instance, over the first several days as cheese cools in bulk containers, moisture is drawn from the warmer interior of the block or barrel to their cooler exterior. For example, single 640 pound blocks of reduced fat cheddar commonly have been observed having an interior moisture of about 44 percent and an external moisture of about 49 percent. The moisture gradient makes it more difficult to form a cheese block having uniform texture throughout. The exterior surface regions of the cheese block may have a firm, smooth texture while the core or central portions of these cheeses may be crumbly or cracked, leading to inferior or waste portions. When the cheese is converted to retail pieces (e.g., 8 oz. chunk or shreds), it is difficult to deal with both the dry center portions and the very moist edges. From a consumer's perspective, cheese from the center often is perceived differently from that at the edge, and the latter variety is preferred by the consumers from an organoleptic standpoint. Moreover, when manufacturing reduced fat cheese or high moisture dry salted cheeses, high moisture target levels may be difficult to achieve without the excessive use of cold wash water. The addition of wash water creates a problem for downstream whey processing and waste water treatment, which is relatively costly.
It has been proposed to rest the cheese blocks at the manufacturing temperature for a period of time before cooling them to permit them to equilibrate. However, in reduced fat (higher moisture) content cheeses in particular, resting the cheese after manufacture and prior to cooling, may lead to increased microbial loads in the finished food product.
It also has been known to accomplish the draining and the pressing of the curd with round probes inserted in the curd to assist in the draining of the whey. However, after removal of these round probes, soft white spots have been left in the curd mass where the curd did not fuse satisfactorily, and moisture variations from point to point within the block have been greater than desired. Various treatments of the curd blocks prior to and during curing have not overcome the problem. It has also been known to use a generally V-shaped perforated pressure plate in connection with the pressing of the curd, as shown in U.S. Pat. No. 3,404,009. However, this pressure plate was primarily designed to remove air and is not adapted for the manufacture of large blocks of cheese. Blocks of cheese also have been rotated during curing in an effort to reduce the occurrence of moisture gradients. Such block rotation procedures are labor intensive and add to the manufacturing costs.
There remains a need for new approaches that will provide an improved process for manufacturing large blocks of cheese, such as reduced fat higher moisture cheeses, with more uniform distribution of moisture and texture throughout the cheese block and which reduce the use of excess water. The present invention provides such processes.